Lost motion linkage for fuel pumps



Oct. 22, 1935. J. fzuEsATY A 2,018,170

LOST MOTION LINKAGE FOR FUEL PUMPS Filed SepL 12, 1928 Sttomego.

Patented Oct. 22, 1935 Joseph Zubaty,

assignments, Detroit, Mich.,

Flint, Mich., assigner, by mesne to General Motors Corporation,

a corporation of Delaware Application September 12, 1928, Serial No. 305,423

1 Claim.

wherein connection with internal combustion engines; and it is-a special object of this invention I to provide reliable and rugged, but comparatively light and quiet, intermediate means for transmission of variable intake strokes from some pump-actuating element, such as an oscillating lever or'rocker arm which may have a uniform throw,.to a pumpdiaphragm stem, or the like.

Alternative lost-motion or thrust-refusing devices having heretofore been proposed for use in transmitting variable intake strokes from an actuating lever, assumed to have an invariable stroke, to a pressure-responsive pumping element (said pumping element being typically a diaphragm secured to a handling member in the general manner suggested in an application by Abraham M. Babitch, S. N. 123,370; filed July 19, l1926) the present invention permits the'use, in transmitting tension from such an actuating lever to a `pumping member, of a handling member in the lform of a reduced diaphragm stem downwardly terminating in a head which may form a stop element; it proposes the interposition, between said lever and said stem, of -a special link having but limited pivotal play relatively to said actuating lever; and, in preferred embodiments of this invention, saidlever being provided with means resiliently holding a motion-receiving arm thereof in constant engagement with a cyclically moving engine part (such as a cam or eccentric imparting to it a uniform reciprocation') the neighboring ends of the mentioned lever and the mentioned stem may both comprise special heads, these heads being respectively so milled out or so forked or otherwise shaped as to provide one or both of the movable members referred to with a stop surface or surfaces adapted to cooperate with a stop surface or surfaces provided upon or by said link and limiting, without undue contact noise, the range of movement permitted thereto. The invention herein disclosed differs further from numerous alternative forms referred to in that, even when built-up pressure holds a pump diaphragm down, there must herein occur at least some slight wobbling of a diaphragm stem, producing corresponding slight undulations in a pump diaphragm; and these undulations must continue so long as the mentioned lever is rocked upon its pivot;4 but the feature here referred to may be of less practical importance than: (l) a shortening of the pump body,-which diminishes the material required therein and the weight thereof;l (2) a diminution of the diaphragm (Cl. 10S-215) stem-this being favorable to quick changes im the direction of itsmovement; (3) a reduction in the total number of parts and (4) inthe work required thereon; and (5) a facility of assembly. To al1 of these advances the use of a link or parallel links conditionally functioning as an inward extension of an actuating lever is favorable.

Other objects of this invention, involving the use of a lost-motion link or links whose longitudinal axis or axes may extend more nearly horizontal than vertical, may be best appreciated from the following description of an illustrative embodiment thereof, taken in connection with the appended claim and the accompanying drawing.

vIn the drawing: f

Figure 1 is, for the most part, a substantially median vertical section through a pump illustrating this invention,y the solid lines and dotted lines being respectively used to indicate the positions occupied by the movable members at the end of an expulsion stroke and at the end of an intake stroke during periods wherein the pressure Within a pump chamber is comparatively low.

Figure 2 is a vertical sectional view, corresponding Ato lower portion of Figure 1, but showing relative positions to which Various parts are depressed, and a type of lost motionI which occurs when the pumping element,4 shown as a flexible diaphragm,

Referring rst to the conventional parts of the fuel pump illustrated, a main structural element (in the form of a body castingV Il) and a sub-` sidiary structural element (in the form of a cover casting I2) are shown as cooperating in the retention of a flexible diaphragm I3. The latter is adapted to serve as areciprocabl'e pumping member byv varying the cubic contents of a pump chamber I4,-shown as provided in the cover l casting I2.

The cover casting I2 may include a valved inlet passage I5 and a valved outlet passage I6; an oscillable actuating member in a form of a rocker arm or lever, shown pivoted to the main casting Il by`a pin Il, may'comprise an inner" arm or member I8 and an outer arm or member I9, the latter-being engageable by some cyclically moving part of an engine 20,-such as a cam 2l upon a camshaft or a crankshaft 22; and means such as a compression spring 23, shown as interposed between an'apertured web 24, comprisingin the main casting II, a cupped disc 25, engaging the diaphragm I3, may be employed resiliently to effect expulsion strokes of said phragm, or its equivalent.

'I'he diaphragm I 3, shown as secured between disc and an oppositely cupped disc 28 by means comprising washers 21, 28 and 28 and a nut 29, may be manipulated by any suitable handling membenquch as a reduced stem 30; and the present invention should be understood as relating more particularly to a novel and advantageous connecting or motion-transmitting means,

including parts of the mentioned tension-transf mitting stem 90 and neighboring parts of the inner lever member I9 and including also a special lever-extending link or links' lL-the latter being suitably interposed yfor a conditional or variable transmission of motion from said lever to said stem, or its equivalent.

Ahead 32 upon the lever member Il is shown as comprising a boss 33. constantly pressed upward by a cupped plate 34, serving to receive a restorative compression spring I5. 'I'he latter may be seated in a suitable depression 39 in a removable bottom closure plate 31; and, instead of providing any separate means for the guidance 'of the lower end of any part of the diaphragm stem l0, or connecting any link or lever extension therewith at an intermediate level, it is considered preferable,...providing `said stem with a head 38 and providing the heads 32. and I9 i respectively with pins 39 and 40, to pivot upon said pins the mentioned lever-extending link 3I,-this link being shown as having its axis disposed in a plane which, although variable according to the extent to which the diaphragm I3 may be held down by internal pressure, departs less from horizontality than from verticality; and

any preferred means may be employed to prevent the inner end of said link from so rising as to exceed a predetermined angular relationship, conditionally constituting it an extension of said lever.

If, as shown, the pins I1, 99 and ll are seated in bored or other cylindrical bearing openings, it will be obvious that any transverse web 24 included in the element II must be provided with having sumcient diameter to allow the stem some play therein. The end of the stem 30 and what has been referred to as the inner end of the mentioned actuating lever are both shown as provided with stop surfaces such as might be produced' by milling; and the momentary engagements of thelever stop surface 42 and the step stop surface by cgiperating with stop surfaces 42 and 43 upon the leverextending link 3i, may be assumed ,to be substantially simultaneous during full-stroke pumping; but it should be noted that either of the mentioned pairs of cooperating stop surfaces is suillcient for the conditional transmission of motion in the indicated manner; and that the making of any actual contact at 44, when the stem 30 5 is held down by pressure above diaphragm I9 and the inner -I8 of theactuatinglever is simultaneously uplifted by cam"2l,'ma'y be of subordinate importance or even undesirable.

During operation against low pressures, it will 10 be seen that, as suggested in Figure l, the leverextending link 3| may maintain a substantially unvarying angular relationship to any actuating member such as that-,comprising arms I8 and I9;

Abut that, `wheneverthe pressure within chamber 15 I 4 becomes such as to depress the diaphragm I3, and thereby the stem 30, toy substantially the level implied by a showing in Figure 2, although the rocking of the arm I 8 upon the pivot I1 may then produce a perceptible wobbling of the stem 20 3,0 as a result of variationsin the substantially horizontal distancebetween the centers of the pins II and 40 (as pin 39 oscillates between ,the full line position and the double line position shown in Figure 2) the rresultant undulation in 25 the diaphragmL I3, or itsequivalent. mayfbeflwith- Y out practical pumping eii'ect. ,v i- Although the foregoing description yhas includ-` p ed but one complete embodiment of this invention, it should be understood not only that vari- 30 slightest departure from the spirit and scopeof this invention, as the same is indicated in the above and the following claim. A

I claim: i

A fuel pump having a pump chamber, a movable pumping member, arstem carried thereby.

a spring operable upon said pumping member to l reduce the pump chamber capacity, a leverpivoted to said pump and having opposed work and y power arms, a link pivoted to said stem and to the work arm of said lever, said link and said stem, and said link and said lever having coi5. operating faces adapted to engage and limit relative movement therebetween, mechanical means to engage the power armand rock said lever inV one direction of rotation only whereby said lever together with the link, when' said faces are in 50 engagement, operate as a rigid unit to produce a suction stroke of said pum JOSEPH ZUBATY. 

